Uniform internal crosslinked sodium alginate film and preparation method thereof

Abstract

The invention discloses a uniform internal crosslinked sodium alginate film and a preparation method thereof. The uniform internal crosslinked sodium alginate film comprises the following components in parts by weight: 1-5 parts of sodium alginate, 0.05-1 part of chitosan oligosaccharide-calcium complex compound, 0.05-1 part of 0.1 M NaOH solution, 1-5 parts of organic acid, 2-10 parts of glycerinand 40-85 parts of deionized water. A uniform calcium-crosslinked sodium alginate film is prepared by creatively taking the chitosan oligosaccharide-calcium complex compound as a sodium alginate internal crosslinking agent, regulating the pH value of a system and uniformly releasing divalent calcium ions in a sodium alginate film forming solution, so that the problem of film forming nonuniformitycaused by superlow local crosslinking degree of local overcrosslinking in an external crosslinking technology is overcome; meanwhile, the crosslinking degree of the film can be regulated and controlled by regulating the proportion of sodium alginate to the oligosaccharide-calcium complex compound; in addition, chitosan oligosaccharide released by the chitosan oligosaccharide-calcium complex compound can also make the film have a certain antibacterial property, so that the uniform internal crosslinked sodium alginate film has a good application prospect in fields of food industry and medicines.

Description

technical field [0001] The invention relates to the field of sodium alginate-based hydrogel, in particular to a uniform internal crosslinked sodium alginate film and a preparation method thereof. Background technique [0002] Sodium alginate is a natural linear polysaccharide extracted from brown algae and sargassum, which is composed of β-1,4-D mannuronic acid (M unit) and α-1,4-D guluronic acid (G unit) is a random linear block copolymer, its structure is as follows figure 1 As shown, it consists of three residues: consecutive G-unit residues (GG), consecutive M-unit residues (MM) and GM mixed residues (GM). [0003] As a natural polysaccharide, sodium alginate is widely used in chemistry, biology, medicine, food and other fields due to its excellent properties, such as degradability, film-forming property, and compatibility; but its poor mechanical properties limit its application. Studies have shown that the G units in sodium alginate molecules can quickly cross-link ...

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Problems solved by technology

Ca 2+ The cross-linking reaction with sodium alginate has the advantages of fast reaction speed / mild reaction conditions. Therefore, calcium chloride solution is often used in the preparation of sodium alginate gel. At present, the preparation of sodium alginate gel is generally through Ca 2+ The foreign link technology, which will soon contain Ca 2+ The solution is mixed and stirred with the sodium alginate solution, but when using the solution casting method to prepare the sodium alginate gel film, whether the calcium chloride solution is added to the sodium alginate solution or the sodium alginate solution is added to the calcium chloride solution, due to Ca 2+ It will quickly undergo ion complexation with the G unit it contacts to form a cross-linked structure, and once the cross-linked structure is generated, Ca 2+ It is difficult to diffuse into the cross-linked structure, which makes it difficult for the G units contained in the cross-linked structure to interact with Ca 2+ Therefore, this cross-linking technology often leads to local over-cross-linking of sodium alginate, and local cross-linking is too low, resulting in uneven gel, which cannot meet the special requirements of some applications

Some studies have proposed that the internal cross-linking technology is to control the Ca 2+ Uniform and slow release to control the uniformity of the gel film, but this internal crosslinking technology generally uses CaCO3 or CaSO 4 Slowly releases Ca as a calcium source under acidic conditions 2+ , but CaCO 3 CO produced by dissolution under acidic conditions 2 Bubbles will affect the film-forming properties of the gel, while CaSO 4 Medium SO 4 2- The introduction of the potential uncertainty risk for the application of gel film in food preservation and other aspects

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